Wireless radio links connect mobile phones and other devices to cellular networks, which also connect to the internet, providing basic voice communications and a wide variety of other services such as short messaging, email, internet access and other business applications. The radio coverage of a typical mobile phone application varies from a few hundred meters in small cell applications to several miles in macro-cell applications in rural areas. Wireless local area networks, referred to as “WiFi,” enable portable computing devices such as laptop and smart phones to connect seamlessly to the internet. The coverage of WiFi is up to a hundred meters. Bluetooth is a wireless technology with even smaller coverage up to 10 meters. Bluetooth technology is widely used in mobile phones for wireless connection between peripheral devices and a mobile device nearby.
Wireless communication systems at each side of the radio link, regardless of coverage sizes, typically have at least one transmitter antenna and at least one receiver antenna. Typical antenna configurations include receiver diversity (two or more receiving antennas), transmitter beamforming (two or more transmitting antennas), and MIMO (Multiple Input and Multiple Output) (multiple transmitter and receiver antennas).
In mobile phone communications, one side of the communication link is a mobile station or user equipment while the other side is a base station. In the GSM-based 3GPP family, both GMSK (2G) and EDGE (2.5G) use receiver antenna diversity, while WCDMA (3G) and LTE (4G) use beamforming and/or MIMO. GMSK/EDGE typically involves time division multiple access (TDMA) (physical layer link) technology, WCDMA uses code division multiple access (CDMA) technology, and LTE uses orthogonal frequency division multiple access (OFDMA) technology for the downlink and single channel-frequency division multiple access (SC-FDMA) technology for the uplink.